EUV Photomask Dry Cleaning With Hydrogen Radicals

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Solution Overview

Problem

Conventional wet cleaning methods for EUV photomasks are time-consuming and can damage the photomask, leading to defects and contamination, especially during the de-attaching and re-attaching processes of the pellicle, and are not efficiently integrated into the semiconductor manufacturing process.

Innovation Solution

A dry cleaning method using hydrogen radicals to remove carbon-containing contaminants from EUV photomasks, which can be performed at the FAB site, reducing the cleaning time to approximately 0.2 days and preventing material oxidation and damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wet cleaning methods are used for EUV photomasks, then cleaning effectiveness is achieved, but the photomask is damaged and defects are caused

Engineering Contradiction:

Improvephotomask integrityVSAvoidmaterial damage and oxidation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the cleaning parameters from wet chemical methods to dry plasma-based methods, altering the physical and chemical state of the cleaning process. This transformation eliminates liquid contact that causes oxidation and damage, while maintaining effective contaminant removal through controlled plasma reactions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs an inert plasma environment for cleaning photomasks, replacing wet chemical atmospheres with controlled dry plasma conditions. This inert environment prevents oxidation and chemical damage to the photomask materials while still enabling effective cleaning through plasma-mediated reactions.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Productivity

If conventional wet cleaning processes are used, then contaminants are removed, but cleaning time is excessive (5 days or more)

Engineering Contradiction:

Improvecleaning speedVSAvoidcleaning cycle duration

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent replaces mechanical and chemical wet cleaning systems with a plasma-based dry cleaning system. This substitution enables much faster cleaning cycles (reducing from 5+ days to significantly shorter durations) while maintaining or improving cleaning effectiveness through the high reactivity of plasma species.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements continuous plasma cleaning processes that can operate without interruption, eliminating the multiple sequential steps required in conventional wet cleaning methods. This continuous action maintains constant cleaning effectiveness throughout the process, maximizing productivity while minimizing total cycle time.

Inventive Principle:

Principle #20Continuity of useful action

3Ease of manufacture

If pellicle de-attaching and re-attaching is performed during wet cleaning, then cleaning access is achieved, but contamination and damage occur

Engineering Contradiction:

Improvecleaning accessibilityVSAvoidcontamination during handling

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent maintains the pellicle attached during dry plasma cleaning by creating an inert plasma environment that prevents contamination. The inert atmosphere protects the photomask and pellicle from environmental contaminants during the cleaning process, eliminating the need for de-attaching and re-attaching operations that would expose the components to contamination risks.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The dry cleaning method effectively removes contaminants without damaging the photomask, improving the photomask's lifetime and product yield by integrating the cleaning process into the semiconductor manufacturing workflow, reducing the risk of defects and material deterioration.

Implementation Method 1

providing hydrogen radicals to the chamber; and exposing the reflective photomask to the hydrogen radicals

Methodology Applied

Scientific EffectHydrogen radical reaction: Chemical Bonding

Data Source

PatentUS11809076B2Cleaning method, method for forming semiconductor structure and system thereof

Publication Date: 2023.11.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for cleaning a reflective photomask, a method of manufacturing a semiconductor structure, and a system for forming a semiconductor structure are provided. The method for cleaning a reflective photomask includes placing a photomask in a first chamber, and performing a dry cleaning operation on the photomask in the first chamber, wherein the dry cleaning operation includes providing hydrogen radicals to the first chamber, generating hydrocarbon gases as a result of reactions of the hydrogen radicals, and removing the hydrocarbon gases from the first chamber.